Enhanced Mobility to Home Base Station Cells

ABSTRACT

Cell relocation procedures to address handover between a macro radio network controller (RNC) and a home base station in a wireless communication network, while accounting for access control or membership verification procedures needed to support a Closed Subscriber Group (CSG) at the home base station. An example method begins with the receiving of a request for handover of the mobile terminal from an RNC of the macro wireless network. A closed subscriber group (CSG) identifier for the home base station and a cell access mode for the home base station are then sent, to a core network node associated with the macro wireless network, for use by the core network node in membership verification or access control for the mobile terminal. In response, the home base station receives a CSG membership status for the mobile terminal from the core network node.

RELATED APPLICATION

This application claims the benefit of and priority to co-pending U.S.patent application Ser. No. 13/593,692, filed 24 Aug. 2012, which claimspriority to U.S. provisional application Ser. No. 61/540,245, filed 28Sep. 2011. The entire contents of said U.S. patent application and U.S.provisional application are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to heterogeneous networks, and moreparticularly relates to methods and apparatus for handing over mobileterminals from a Radio Network Controller in a macro wireless network toa home base station supporting a closed subscriber group.

BACKGROUND

The 3rd-Generation Partnership Project (3GPP) is continuing developmentof specifications for the Universal Terrestrial Radio Access Network(UTRAN). That continuing development includes improved support forheterogeneous networks. In heterogeneous networks (also known asHetNets), an existing homogeneous network, e.g., a cellular networkcomprising several similarly-sized macro cells, is overlaid withadditional lower-power cells, such as femtocells, which can be referredto as Home Node B's or HNBs. These femtocells may be configured as homebase stations to support connectivity for only a limited set ofsubscribers, known as a Closed Subscriber Group (CSG).

HNBs may operate in open, closed, or hybrid access modes. In open accessmode, the HNB appears as a normal base station to mobile terminals (UEs,in 3GPP terminology), and can freely provide services to non-membermobile terminals. In closed access mode, the HNB only provides servicesto members of its CSG. In the hybrid access mode, the HNB providesservices to both its members and also to non-members, but prioritizesmembers over non-members.

The Wideband Code Division Multiple Access (WCDMA) HNB architecture hasbeen developing at a very high rate in the last few years. One of thedevelopments concerns improving mobility procedures for UEs movingbetween HNBs as well as for UEs moving between HNBs and macro cells.Some examples of mobility that are currently supported include thefollowing:

-   -   Hard handover (HHO) mobility, based on Radio Access Network        Application Part (RANAP) signaling. Hard handovers can be        carried out between any type or source or target, including, for        example, a source macro Radio Network Controller (RNC) and a        target HNB with any sort of cell access mode (closed, hybrid or        open). This type of mobility follows procedures specified in the        3GPP standards document entitled “UTRAN lu interface; Radio        Access Network Application Part (RANAP) signaling”, 3GPP TS        25.413, v. 10.2.0 (June 2011), and is based on the principle        that access control and member verification processes, which        determine whether a mobile terminal should be permitted to enter        a closed mode cell or whether a mobile terminal should be        prioritized within a hybrid mode cell, are carried out in the        core network.    -   HNB-to-HNB hard handover via the “lurh” interface, as described        in section 5.7 of “UTRAN Architecture for 3G Home Node B (HNB);        Stage 2,” 3GPP TS 25.467, v. 10.2.0 (June 2011). This type of        mobility is possible between HNBs only and can occur between        open access HNBs or between hybrid access HNBs with the same        CSG, or between closed access HNBs with the same CSG. This type        of mobility occurs without any involvement of the core network,        i.e., mobility signaling is handled within the HNB gateway        domain without ever exiting such domain.    -   HNB-to-HNB soft handover via the “lurh” interface, as per        section 5.7.3 of 3GPP TS 25.467, v. 10.2.0. This type of        mobility is possible in the same scenarios as for the HNB-to-HNB        hard handovers discussed above, with the difference being that        mobility happens in a “soft” manner, such that the UE always        maintains at least one radio link with the core network, unlike        a hard handover, in which old radio links in the UE are removed.

The 3GPP has recently prioritized a number of mobility scenarios whereenhanced mobility procedures are desired. Notably, the only mechanismcurrently existing to allow mobility between macro RNCs and HNBs is touse the RANAP-based hard handover mobility procedures, as describedabove, which are carried out via the core network. In these procedures,access control (performed for handover to closed access CSG cells) andmembership verification (performed for handover to hybrid CSG cells) arecarried out in a centralized manner by the core network, which holdssubscriber information. However, this type of mobility is not efficientin terms of performance, due to the fact that every mobility signalingis routed via the CN, generating large delays.

SUMMARY

Existing cell relocation procedures are modified to address handoverbetween a macro radio network controller (RNC) and a home base stationin a wireless communication network, while accounting for access controlor membership verification procedures needed to support a ClosedSubscriber Group (CSG) at the home base station.

Several methods for performing a handover between an RNC in a macrowireless network and a home base station supporting a CSG in a wirelesscommunication network, as carried out by the home base station, aredisclosed. An example method begins with the receiving of a request forhandover of the mobile terminal from an RNC of the macro wirelessnetwork. A closed subscriber group (CSG) identifier for the home basestation and a cell access mode for the home base station are then sent,to a core network node associated with the macro wireless network, foruse by the core network node in membership verification or accesscontrol for the mobile terminal. In response, the home base stationreceives a CSG membership status for the mobile terminal from the corenetwork node.

In some embodiments, the home base station is operating in hybrid accessmode and the method further includes a determination by the home basestation, based upon the CSG membership status received from the corenetwork node, of whether or not to prioritize the mobile terminal in theCSG. In some of these embodiments, the home base station may temporarilyadmit the mobile terminal to the CSG, prior to receiving the CSGmembership status for the mobile terminal from the core network node,based on a reported CSG membership status for the mobile terminalreceived in the request for handover. In some cases, the reported CSGmembership status indicates that the mobile terminal is a member of theCSG but the CSG membership status received from the core network nodeindicates that the mobile terminal is not a member of the CSG, in whichthe method may further include de-prioritizing the mobile terminal'saccess to the home base station in response to receiving the CSGmembership status from the core network node.

In other embodiments, the home base station is operating in closedaccess mode, in which case the method may further include, based uponthe CSG membership status received from the core network node, whetheror not to admit the mobile terminal to the CSG. In some cases, the homebase station may temporarily admit the mobile terminal to the CSG, priorto receiving the CSG membership status for the mobile terminal from thecore network node, based on a reported CSG membership status for themobile terminal received in the request for handover, but thendisconnect the mobile terminal from the home base station upondetermining that the CSG membership status received from the corenetwork indicates that the mobile terminal is not a member of the CSG.

In some embodiments, the request for handover received from the radionetwork controller and the CSG membership status received from the corenetwork node are received at the home base station via a home basestation gateway. In these embodiments, the closed subscriber group (CSG)identifier and the cell access mode are likewise sent to the corenetwork node via the home base station gateway. In some cases, the homebase station is a Home NodeB connected to a Universal Terrestrial RadioAccess Network (UTRAN), and the request for handover is a Radio NetworkSubsystem Application Part (RNSAP) Enhanced Relocation Request. In someof these embodiments, the CSG ID and the cell access mode are sent tothe core network node via a Radio Access Network Application Part(RANAP) Enhanced Relocation Complete Request message and the CSGmembership status is received via a RANAP Enhanced Relocation CompleteResponse message.

Other embodiments of the invention include home base station apparatusdetailed herein. Of course, the present invention is not limited to theabove-summarized features and advantages. Indeed, those skilled in theart will recognize additional features and advantages upon reading thefollowing detailed description, and upon viewing the accompanyingdrawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an example heterogeneous wireless communicationnetwork.

FIG. 2 illustrates additional details of the example heterogeneouswireless communication network.

FIG. 3 illustrates still further details of the example heterogeneouswireless communication network.

FIG. 4 illustrates a call flow diagram for a prior art Enhanced ServingRadio Network Subsystem (SRNS) handover procedure for handover betweentwo RNCs.

FIG. 5 is a call flow diagram for a modified enhanced SRNS handoverprocedure, for handover between a RNC and a HNB.

FIGS. 6A and 6B together illustrate an “Enhanced Relocation CompleteRequest” message of the procedure of FIG. 5.

FIG. 7 illustrates an “Enhanced Relocation Complete Response” message ofthe procedure of FIG. 5.

FIG. 8 is a flow chart illustrating a method for performing a handoverbetween a macro RNC and a HNB in the heterogeneous wirelesscommunication network.

FIG. 9 is another flow chart illustrating a method for performing ahandover between a macro RNC and a HNB in the heterogeneous wirelesscommunication network.

FIG. 10 is a block diagram illustrating components of a home basestation according to several embodiments of the invention.

DETAILED DESCRIPTION

In the discussion that follows, specific details of particularembodiments of the present invention are set forth for purposes ofexplanation and not limitation. It will be appreciated by those skilledin the art that other embodiments may be employed apart from thesespecific details. Furthermore, in some instances detailed descriptionsof well-known methods, nodes, interfaces, circuits, and devices areomitted so as not obscure the description with unnecessary detail. Thoseskilled in the art will appreciate that the functions described may beimplemented in one or in several nodes. Some or all of the functionsdescribed may be implemented using hardware circuitry, such as analogand/or discrete logic gates interconnected to perform a specializedfunction, ASICs, PLAs, etc. Likewise, some or all of the functions maybe implemented using software programs and data in conjunction with oneor more digital microprocessors or general purpose computers. Wherenodes that communicate using the air interface are described, it will beappreciated that those nodes also have suitable radio communicationscircuitry. Moreover, the technology can additionally be considered to beembodied entirely within any form of computer-readable memory, includingnon-transitory embodiments such as solid-state memory, magnetic disk, oroptical disk containing an appropriate set of computer instructions thatwould cause a processor to carry out the techniques described herein.

Hardware implementations of the present invention may include orencompass, without limitation, digital signal processor (DSP) hardware,a reduced instruction set processor, hardware (e.g., digital or analog)circuitry including but not limited to application specific integratedcircuit(s) (ASIC) and/or field programmable gate array(s) (FPGA(s)), and(where appropriate) state machines capable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors or one or more controllers, and theterms computer, processor, and controller may be employedinterchangeably. When provided by a computer, processor, or controller,the functions may be provided by a single dedicated computer orprocessor or controller, by a single shared computer or processor orcontroller, or by a plurality of individual computers or processors orcontrollers, some of which may be shared or distributed. Moreover, theterm “processor” or “controller” also refers to other hardware capableof performing such functions and/or executing software, such as theexample hardware recited above.

FIG. 1 illustrates an example heterogeneous network 10 including a macrobase station (MBS) 12 and a home base station (e.g., a HNB) 16. Themacro base station 12 supports a macro cell coverage area 14. The HBS 16supports a CSG within a smaller coverage area 18 that itself is at leastpartially within the macro cell coverage area 14.

FIGS. 2 and 3 illustrate additional details of the example heterogeneouswireless communication network 10. Referring to FIG. 2, the network 10includes a plurality of MBSs 12, and a plurality of HNBs 16. RNCs 22 a,22 b each control a plurality of MBSs 12. Likewise, a HNB gateway (HNBGW) 24 controls a plurality of HNBs 16. The RNCs 22 a, 22 b and HNB GW24 are operative to communicate via core network (CN) 26.

Referring to FIG. 3, the mobile terminals (e.g. UEs) 20 can communicatewirelessly with their respective HNB 16 via a “Uu” interface of the HNB.Also, the HNBs 16 can communicate with each other via an “lurh”interface, and can communicate with the HNB GW 24 via an “luh”interface. The HNB GW 24 relays communications between the HNBs 16 andthe core network 26 via an “lu” interface, and to other HNB GWs via an“lur” interface. The security gateway 19 performs encryption/decryption,and may be implemented either as a separate physical element, or may beintegrated into, for example, the HNB GW 24.

As discussed above, HNBs may operate in open, closed, or hybrid accessmodes. These access modes have been referred to in standardizationefforts as both “cell access modes” and “CSG access modes”; while theseterms should be understood to be equivalent, the term “cell accessmodes” is used herein. In open access mode, the HNB appears as a normalbase station to mobile terminals (UEs, in 3GPP terminology), and canfreely provide services to non-member mobile terminals. In closed accessmode, the HNB only provides services to members of its CSG. In thehybrid access mode, the HNB provides services to both its members andalso to non-members, but prioritizes members over non-members.

As discussed above, the only mechanism currently existing to allowmobility between macro RNCs and HNBs is to use the RANAP-based hardhandover mobility procedures, as described above, which are carried outvia the core network. In these procedures, access control (performed forhandover to closed access CSG cells) and membership verification(performed for handover to hybrid CSG cells) are carried out in acentralized manner by the core network, which holds subscriberinformation. However, this type of mobility is not efficient in terms ofperformance, due to the fact that all mobility signaling is routed viathe core network, generating large delays.

Notably, however, the 3GPP has standardized an alternative way to carryout HHO mobility between RNCs. This enhanced procedure is known as“Enhanced Serving Radio Network Subsystem (SRNS) Relocation,” and iscarried out via RNSAP signaling over the “lur” interface between the twoRNCs involved in the mobility. This type of mobility is described in the3GPP document “General Packet Radio Service (GPRS); Service descriptionStage 2 (Release 10)”, 3GPP TS 23.060, v.10.4.0 (2011-06), and isillustrated as procedure 100 in the call flow diagram of FIG. 4. Thistype of mobility improves signaling performance in that the RNSAPmessages are routed via the peer-to-peer “lur” interface between RNCs,and do not need to pass through the core network 26.

Referring to FIG. 4, the illustrated Enhanced SRNS Relocation procedure100 demonstrates the implementation of HHO between a serving macro RNC22 a and a target macro RNC 22 b. As shown at step 101, a decision ismade to relocate the UE 20 in question from the serving RNC 22 a to thetarget RNC 22 b. A RNSAP Enhanced Relocation Request is transmitted fromthe RNC 22 a and is acknowledged by the RNC 22 b, as shown at step 102and 104. The serving RNC 22 a then transmits a RNSAP Relocation Commitmessage, as shown at step 106. Notably, steps 102-106 are conducted viathe “lur” interface between the RNCs 22 a-b.

RNC 22 a transmits a Radio Resource Control (RRC) Conn. ReconfigurationRequest message to the UE 20 and the UE 20 transmits a message to thetarget RNC 22 b confirmation completion of the reconfiguration, as shownat steps 108 and 110. As seen at steps 112 and 114, the target RNC 22 bthen transmits a message to the CN 26 to complete the request completionof the relocation and the CN 26 transmits a complete response to thetarget RNC 22 b. The target RNC 22 b then confirms the relocation, asshown at step 116, and transmits a RANAP “lu” release message to theserving RNC 22 a, as shown at step 118.

Because the Enhanced SRNS Relocation procedure shown in FIG. 4 is onlycarried out between macro cells that are accessible by any UE (see,e.g., macro cell 14, in FIG. 1), there has never been any performance ofaccess control or membership verification in this type of mobility.Thus, it is not possible in the existing Enhanced SRNS Relocationprocedure 100 to carry out access control or membership verification fora UE moving to a CSG cell.

The Enhanced SRNS Relocation procedure 100 also lacks some features ofthe RANAP-based hard-handover mobility discussed earlier. For example,in the RANAP-based HHO mobility procedures, the results of the accesscontrol or membership verification processes are passed to the targetHNB via a “RANAP Relocation Request,” in the form of a “CSG MembershipStatus” information element (IE). This CSG Membership Status IE is setto “member” or “non-member” (see 3GPP TS 25.413 V10.2.0).

In the event the UE membership to the target CSG happened to changewhile the UE is connected to that cell, the current specifications forRANAP-based HHO mobility allow a “RANAP Common ID” message to be sentfrom the CN 26 to the HNB; this RANAP Common ID message can include the“CSG Membership Status” IE. Upon receipt of this IE, the target HNB canupdate the UE membership status and treat the UE accordingly. Forexample, the target HNB can disconnect the UE if it is no longerpermitted to be connected to the cell, or de-prioritize the UE in ahybrid access mode cell if the UE is no longer a member of the CSG.However, in the Enhanced SRNS Relocation procedure 100 there are nomechanisms to pass the results of access control or membershipverification from CN to target HNB.

Additionally, the RANAP-based HHO mobility procedures include amechanism to carry out CSG ID validation. CSG ID validation is a processaccording to which the CSG ID reported by the UE as part of the mobilitymeasurement report is checked at the target HNB. If the CSG ID reportedby the UE is the same as the CSG ID broadcast by the target HNB, thenthe validation passes. If the validation fails, the target HNB has theoption of either failing the mobility procedure (if the HNB operates asa closed CSG cell) or successfully completing the mobility procedure (ifthe HNB operates as a hybrid CSG cell).

If the validation fails it means that the CN received an incorrect CSGID in the “RANAP Relocation Required” message. In this case, if themobility procedure is successfully concluded, the target HNB reports itsown CSG ID to the CN 26, in order to allow the CN 26 to charge thesubscriber according to the correct CSG ID accessed. The current 3GPPspecifications allow for a target HNB to report its own CSG ID in the“RANAP Relocation Request Acknowledge” message, hence allowing the CN toapply the correct charging for the subscriber. However, in the EnhancedSRNS Relocation procedure 100, reporting of the target CSG ID to the CN26 is not supported.

Several embodiments of the present invention address one or several ofthese shortcomings of existing procedures through modifications of theexisting Enhanced SRNS Relocation procedures. Thus, FIG. 5 illustrates aprocedure 200 in which the Enhanced SRNS Relocation procedure 100 ismodified to support HHO mobility between a macro RNC 22 and closed orhybrid HNBs 16, and to address several of the problems discussed above.These enhancements include sending information to the CN 26 about thetarget CSG cell the UE 20 is accessing via mobility. This permits the CN26 to carry out Access Control or Membership Verification, and furtherfacilitates the correct charging in the event of CSG ID validationfailure at the target. In some embodiments, these enhancements alsoinclude allowing the network to reply to the target HNB with the CSGMembership Status of the cell the UE is trying to access.

Referring to FIG. 5, the illustrated procedure 200 is conducted betweena serving macro RNC 22 a and a target HNB 16. A UE 20 transmits ameasurement report to its serving RNC 22 a, as shown at step 202. Thismeasurement report includes an indication of whether the UE is part ofthe CSG of the target HNB 16. As shown at step 204, the serving RNC 22 amakes a decision whether to relocate the UNC to the target HNB 16 ornot.

As shown at step 206, a RNSAP Enhanced Relocation Request message istransmitted from the RNC 22 a to the target HNB 16 via the HNB GW 24. Inresponse, the target HNB 16 transmits an acknowledgement message back tothe serving RNC 22 a via the HNB GW 24, as shown at step 208. Uponreceiving the acknowledgement, the serving RNC 22 a transmits a RNSAPRelocation Commit message to the target HNB 16, as shown at step 210.Note that steps 206-210 collectively correspond to a “relocationpreparation” phase. In one example, in steps 206-210 the HNB GW 24communicates with the RNC 22 a via the “lur” interface that istraditionally used only by RNCs. Advantageously, such use of the “lur”interface, and the appearance of the HNB GW 24 as a RNC to the CN 26,enables backwards compatibility with existing RNCs.

If the UE 20 has earlier reported its Membership Status in theMeasurement Report (step 202), then the “CSG Membership Status” IEincluded in the “RANAP Enhanced Relocation Information Request” IEcarried by the Enhanced Relocation Request of step 206 should be thesame as what was reported by the UE 20. If no CSG Membership Status wasreported by the UE 20 in the Measurement Report, then the CSG MembershipStatus included in the Enhanced Relocation Request (206) should be setto “non-member,” in order to avoid incorrect prioritization by thetarget HNB 16.

In an “execution phase” that follows the “relocation preparation” phase,the macro RNC 22 a transmits a Radio Resource Control (RRC) Conn.Reconfiguration Request message to the UE 20, as shown at step 212. Inresponse, as shown at step 214, the UE 20 transmits a message to theT-HNB 16, via macro RNC 22 a, confirming completion of thereconfiguration for handover.

After the execution phase (steps 212 and 214), the HNB GW 24 relays a“RANAP Enhanced Relocation Complete Request” message 60 from the targetHNB 16 to the CN 26, as shown at step 216. Notably, this messageincludes both a CSG identifier (ID) and an information elementspecifying a cell access mode (alternatively referred to as a “CSGaccess mode”). FIGS. 6A and 6B together illustrate an example of themessage 60 sent in step 216 of the enhanced procedure of FIG. 5. A firstportion 62 of the message 60 is sent in both step 112 of procedure 100,as well as in step 216 of procedure 200. A second portion 64 of themessage 60, however, is present only in step 216 of procedure 200. Asshown in FIG. 6B, this second portion 64 includes the CSG ID and cellaccess mode information elements discussed above.

The CSG ID and cell access mode information elements sent in step 216 ofprocedure 200 allow the CN 26 to carry out access control, in the eventthat the HNB 16 is supporting a CSG in closed access mode, or membershipverification, in the event that the HNB 16 is supporting a CSG in hybridaccess mode. Also, by adding the CSG ID to the message of step 216, theCN 26 is able to apply correct charging in the event that the CSGvalidation process fails. CSG validation is possible because the CSG IDreported by the UE 20 in the measurement report of step 202 is includedin the “RANAP Enhanced Relocation Information Request” of step 206.

Once the access control or membership verification is carried out by theCN 26, the CN 26 sends a “RANAP Enhanced Relocation Complete Response”message 70 to the HNB GW 24, which relays the message to the target HNB16. This is shown in FIG. 5 at step 218. Notably, this message 70includes a “CSG Membership Status” indication, with which the CN 26confirms whether the mobile terminal is eligible for inclusion in theCSG of the HNB 16. FIG. 7 illustrates an example of this message 70,which includes a message portion 72 that is sent in both step 114 ofprocedure 100 and also in step 218 of procedure 200. The message 70 alsoincludes a message portion 74 that is sent only in step 218 of procedure200. This message portion 74 includes the “CSG Membership Status”information element.

Once the message 70 of step 218, including the “CSG Membership Status”IE, is received at the HNB 16, the HNB 16 can make a decision whether ornot to admit the UE 20 to its CSG (in closed mode) or whether or not toprioritize the UE in the CSG (in hybrid mode). If the HNB 16 accepts thehandover, the HNB GW 24 relays a “RANAP Enhanced Relocation CompleteConfirm” message from the HNB 16 to the CN 26, as shown at step 220,after which the RANAP lu Release Command and RANAP lu Release Completemessages are exchanged between the CN 26 and the source RNC 22 a, asshown at steps 222 and 224. Optionally, the results of the accesscontrol or membership verification performed by the CN 26 (between steps216 and 218) could be communicated by the CN 26 via the COMMON IDprocedure (not shown), after the Enhanced SRNS Relocation Completeprocedure 200 has been terminated, instead of as part of the RANAPEnhanced Relocation Complete Response message.

The signaling flow diagram of FIG. 5 and the specific message contentsillustrated in FIGS. 6 and 7 provide details of some embodiments of theenhanced techniques for performing a handover between a source RNC in aUTRAN and an HNB connected to the UTRAN. In particular, note that theexample message contents illustrated in FIGS. 6 and 7 are adapted fromand include additions to message elements described in 3GPP TS 25.413,v. 10.2.0 (June 2011).

FIG. 8 is a process flow diagram illustrating a generalized method 300for performing a handover between a macro radio network controller and ahome base station supporting a CSG in a wireless communication network,as carried out by the home base station.

The method 300 begins with the receiving of a request for handover ofthe mobile terminal from a radio network controller of the macrowireless network, as shown at block 302. As shown at block 304, a closedsubscriber group (CSG) identifier for the home base station and a cellaccess mode for the home base station are then sent, to a core networknode associated with the macro wireless network, for use by the corenetwork node in membership verification or access control for the mobileterminal. In response, the home base station receives a CSG membershipstatus for the mobile terminal from the core network node, as shown atblock 306.

In some embodiments of method 300, the home base station is operating inhybrid access mode and the method further includes a determination bythe home base station, based upon the CSG membership status receivedfrom the core network node, of whether or not to prioritize the mobileterminal in the CSG. In some of these embodiments, the home base stationmay temporarily admit the mobile terminal to the CSG, prior to receivingthe CSG membership status for the mobile terminal from the core networknode, based on a reported CSG membership status for the mobile terminalreceived in the request for handover. In some cases, the reported CSGmembership status indicates that the mobile terminal is a member of theCSG but the CSG membership status received from the core network nodeindicates that the mobile terminal is not a member of the CSG, in whichthe method may further include de-prioritizing the mobile terminal'saccess to the home base station in response to receiving the CSGmembership status from the core network node.

In other embodiments, the home base station is operating in closedaccess mode, in which case the method may further include, based uponthe CSG membership status received from the core network node, whetheror not to admit the mobile terminal to the CSG. In some cases, the homebase station may temporarily admit the mobile terminal to the CSG, priorto receiving the CSG membership status for the mobile terminal from thecore network node, based on a reported CSG membership status for themobile terminal received in the request for handover, but thendisconnect the mobile terminal from the home base station upondetermining that the CSG membership status received from the corenetwork indicates that the mobile terminal is not a member of the CSG.

As was shown in the signaling flow diagram of FIG. 5, in someembodiments the request for handover received from the radio networkcontroller and the CSG membership status received from the core networknode are received at the home base station via a home base stationgateway. In these embodiments, the closed subscriber group (CSG)identifier and the cell access mode are likewise sent to the corenetwork node via the home base station gateway. As should be clear fromthe detailed procedures illustrated in FIGS. 5-7, in some embodimentsthe home base station is a Home NodeB (HNB) connected to a UniversalTerrestrial Radio Access Network (UTRAN), and the request for handoveris a Radio Network Subsystem Application Part (RNSAP) EnhancedRelocation Request. In some of these embodiments, the CSG ID and thecell access mode are sent to the core network node via a Radio AccessNetwork Application Part (RANAP) Enhanced Relocation Complete Requestmessage and the CSG membership status is received via a RANAP EnhancedRelocation Complete Response message.

FIG. 9 is a process flow diagram illustrating a closely related variantof the method illustrated in FIG. 8, again as implemented by a home basestation operating a CSG. The illustrated method 400 begins, as shown atblock 402, with determining that a radio network controller in the macrowireless network is requesting a handover of a mobile terminal to thehome base station, for inclusion in the CSG. Next, as shown at block404, the home base station determines, responsive to signaling betweenthe home base station and a core network node associated with the macrowireless network, whether the mobile terminal is eligible for inclusionin the CSG. As shown at block 406, the home base station then decideswhether to admit the mobile terminal to the CSG or whether to prioritizethe mobile terminal, based on whether the mobile terminal is eligiblefor inclusion in the CSG.

In some embodiments, the handover of the methods 300 and 400 is a HHO inwhich existing radio links between the mobile terminal and the servingRNC are removed. The handover eligibility processing performed by the CN26 (and referenced in blocks 304 and 404) includes access control if thecell access mode is closed, or includes membership verification if theCSG access mode is hybrid.

Referring once again to FIG. 3, it will be appreciated that an HNB 16configured to support a closed subscriber group (CSG) within thewireless communication network 10 includes one or more transceivers 80and a controller 82. The one or more transceivers 80 are operative tocommunicate with a mobile terminal 20 in the wireless communicationnetwork 10, and are operative to communicate with the HNB GW 24. Thecontroller 82 is operatively associated with the one or moretransceivers 80.

The controller 82 is configured to receive a request for handover of amobile terminal from a macro RNC 22 to the HNB 16 (see, e.g., step 206in FIG. 5). In one example, the request is received at the HNB GW 24 viaRNSAP signaling between the HNB GW 24 and the macro RNC 22, and is thenrelayed by the HNB GW 24 to the HNB 16 (see, e.g., step 206 in FIG. 5).The controller 82 is further configured to transmit a CSG identifier anda cell access mode to a core network node 28 of the wirelesscommunication network 10 for handover eligibility processing, with theCSG identifier and cell access mode being transmitted to the corenetwork node 28 via the HNB GW 24 (see, e.g., step. 216). In oneexample, HNB GW 24 relays the CSG identifier and cell access mode to thecore network node 28 using RANAP signaling. The controller 82 is furtherconfigured to accept the handover of the mobile terminal 20 from themacro RNC to the HNB responsive to the core network node 28 confirmingthat the mobile terminal is eligible for inclusion in the CSG (see,e.g., step 220).

The operations illustrated in the signaling flow diagram of FIG. 5 andin the process flow diagrams of FIGS. 8 and 9 may thus be implemented ina home base station using a radio transceiver 80 and controller 82, thelatter including appropriate network interface circuitry for carryingout communications with a home base station gateway and/or a corenetwork component. Transceiver 80, of course, includes suitable radiocircuitry for receiving and transmitting radio signals formatted inaccordance with known formats and protocols, such as the formats andprotocols specified by 3GPP for UTRAN.

FIG. 10 thus illustrates features of an example home base station 16according to several embodiments of the present invention. Home basestation 16 comprises a transceiver 80 for communicating with mobileterminals as well as a controller 82 for processing the signalstransmitted and received by the transceiver 80 and communicating withother elements of the communications network via network interface 810.Transceiver 80 includes a transmitter 822 coupled to one or moretransmit antennas 826 and receiver 824 coupled to one or more receiveantennas 828. The same antenna(s) 826 and 828 may be used for bothtransmission and reception. Receiver 824 and transmitter 822 use knownradio processing and signal processing components and techniques,typically according to a particular telecommunications standard such asthe 3GPP standards for Wideband CDMA (W-CDMA) and High-Speed PacketAccess (HSPA). Because the various details and engineering tradeoffsassociated with the design and implementation of such circuitry are wellknown and are unnecessary to a full understanding of the invention,additional details are not shown here.

Controller 82 comprises one or more processors 802, hardware, firmwareor a combination thereof, coupled to one or more memory devices 804 thatmake up a data storage memory 806 and a program storage memory 808.Memory 804 may comprise one or several types of memory such as read-onlymemory (ROM), random-access memory, cache memory, flash memory devices,optical storage devices, etc. Controller 82 further comprises a networkinterface circuit 810, configured to communicate with other networknodes, such as a home base station gateway, again using well knowntelecommunications standards. Once more, because the various details andengineering tradeoffs associated with the design of baseband processingcircuitry for wireless base stations and similar devices are well knownand are unnecessary to a full understanding of the invention, additionaldetails are not shown here.

Typical functions of the controller 82 include modulation and coding oftransmitted signals and the demodulation and decoding of receivedsignals. In several embodiments of the present invention, controller 82is further adapted, using suitable program code stored in programstorage memory 808, for example, to carry out one of the techniquesdescribed above for performing a handover of a mobile terminal from amacro wireless network to the home base station. Of course, it will beappreciated that not all of the steps of these techniques arenecessarily performed in a single microprocessor or even in a singlemodule.

In some embodiments, for example, controller 82 is configured to receivea request for handover of the mobile terminal sent to the home basestation from a radio network controller of the macro wireless networkand to send, to a core network node associated with the macro wirelessnetwork, a closed subscriber group (CSG) identifier for the home basestation and a cell access mode for the home base station, for use by thecore network node in membership verification or access control for themobile terminal. The controller 82 in these embodiments is furtherconfigured to receive a CSG membership status for the mobile terminalfrom the core network node, responsive to sending the CSG identifier andthe cell access mode to the core network node.

All the variations described above for the signaling flow of FIG. 5 andthe process flows of FIGS. 8 and 9 may be applied as well to the homebase station 16 pictured in FIG. 10. For example, in several embodimentsthe controller 82 is further configured to, when said home base stationis operating in hybrid access mode, determine whether or not toprioritize the mobile terminal in the CSG based upon the CSG membershipstatus received from the core network node. The controller 82 in theseembodiments may be further configured to temporarily admit the mobileterminal to the CSG, prior to receiving the CSG membership status forthe mobile terminal from the core network node, based on a reported CSGmembership status for the mobile terminal received in the request forhandover, and may be still further configured to de-prioritize themobile terminal's access to the home base station in response toreceiving the CSG membership status from the core network node, when thereported CSG membership status indicates that the mobile terminal is amember of the CSG and the CSG membership status received from the corenetwork node indicates that the mobile terminal is not a member of theCSG.

In some of these and in other embodiments, the controller 82 is furtherconfigured to, when said home base station is operating in closed accessmode, determine whether or not to admit the mobile terminal to the CSGbased upon the CSG membership status received from the core networknode. In some cases, the controller 82 is configured to, when said homebase station is operating in closed access mode, temporarily admit themobile terminal to the CSG, prior to receiving the CSG membership statusfor the mobile terminal from the core network node, based on a reportedCSG membership status for the mobile terminal received in the requestfor handover, and disconnect the mobile terminal from the home basestation upon determining that the CSG membership status received fromthe core network indicates that the mobile terminal is not a member ofthe CSG.

Advantageously, the methods and apparatus described above provide anenhanced mechanism for HHO mobility between macro RNCs and hybrid/closedCSG HNBs. The novel methods and apparatus discussed above are based onrespecting the principle that a desirable location to perform accesscontrol and membership verification is the core network 26, and arefurther based on the adoption of existing Enhanced SRNS Relocationprocedures (see FIG. 3), and extending them to HNB/RNC mobilityscenarios.

As a further example of an advantage of the present invention,performance of access control and member verification in the corenetwork 26 ensures that subscriber information is securely handled.Additionally, because the methods 300, 400 and HNB 16 described abovereuse portions of existing standardized procedures (e.g. the enhancedSRNS procedure 100 of FIG. 4), these methods and apparatus are backwardscompatible with legacy RNCs.

Examples of several embodiments of the present invention have beendescribed in detail above, with reference to the attached illustrationsof specific embodiments. Because it is not possible, of course, todescribe every conceivable combination of components or techniques,those skilled in the art will appreciate that the present invention canbe implemented in other ways than those specifically set forth herein,without departing from essential characteristics of the invention.Modifications and other embodiments of the disclosed invention(s) willcome to mind to one skilled in the art having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the invention(s) is/arenot to be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of this disclosure. Although specific terms may be employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation. The present embodiments are thus to beconsidered in all respects as illustrative and not restrictive.

What is claimed is:
 1. A method, in a home base station operating aclosed subscriber group (CSG), for performing a handover of a mobileterminal from a macro wireless network to the home base station, themethod comprising: receiving a request for handover of the mobileterminal from a radio network controller of the macro wireless network;sending, to a core network node associated with the macro wirelessnetwork, a closed subscriber group (CSG) identifier for the home basestation and a cell access mode for the home base station, for use by thecore network node in membership verification or access control for themobile terminal; and receiving a CSG membership status for the mobileterminal from the core network node, responsive to sending the CSGidentifier and the cell access mode to the core network node.
 2. Themethod of claim 1, wherein said home base station is operating in hybridaccess mode, the method further comprising determining, based upon theCSG membership status received from the core network node, whether ornot to prioritize the mobile terminal in the CSG.
 3. The method of claim1, wherein said home base station is operating in closed access mode,the method further comprising determining, based upon the CSG membershipstatus received from the core network node, whether or not to admit themobile terminal to the CSG.
 4. The method of claim 1, wherein saidrequest for handover received from the radio network controller and saidCSG membership status received from the core network node are receivedvia a home base station gateway, and wherein the closed subscriber group(CSG) identifier and the cell access mode are sent to the core networknode via the home base station gateway.
 5. The method of claim 1,wherein the home base station is a Home NodeB connected to a UniversalTerrestrial Radio Access Network (UTRAN), and wherein said request forhandover is a Radio Network Subsystem Application Part (RNSAP) EnhancedRelocation Request.
 6. The method of claim 5, wherein the CSG ID and thecell access mode are sent to the core network node via a Radio AccessNetwork Application Part (RANAP) Enhanced Relocation Complete Requestmessage and the CSG membership status is received via a RANAP EnhancedRelocation Complete Response message.
 7. A home base station configuredto support a closed subscriber group within a macro wireless network,the home base station comprising: a transceiver operative to communicatewith a mobile terminal, and a controller configured to: receive arequest for handover of the mobile terminal sent to the home basestation from a radio network controller of the macro wireless network;send, to a core network node associated with the macro wireless network,a closed subscriber group (CSG) identifier for the home base station anda cell access mode for the home base station, for use by the corenetwork node in membership verification or access control for the mobileterminal; and receive a CSG membership status for the mobile terminalfrom the core network node, responsive to sending the CSG identifier andthe cell access mode to the core network node.
 8. The home base stationof claim 7, wherein the controller is further configured to, when saidhome base station is operating in hybrid access mode, determine whetheror not to prioritize the mobile terminal in the CSG based upon the CSGmembership status received from the core network node.
 9. The home basestation of claim 7, wherein the controller is further configured to,when said home base station is operating in closed access mode,determine whether or not to admit the mobile terminal to the CSG basedupon the CSG membership status received from the core network node. 10.The home base station of claim 7, wherein the home base station isconfigured to receive said request for handover and said CSG membershipstatus via a home base station gateway and to send the closed subscribergroup (CSG) identifier and the cell access mode to the core network nodevia the home base station gateway.
 11. The home base station of claim 7,wherein the home base station is a Home NodeB connected to a UniversalTerrestrial Radio Access Network (UTRAN), and wherein said request forhandover is a Radio Network Subsystem Application Part (RNSAP) EnhancedRelocation Request.
 12. The home base station of claim 11, wherein thehome base station is configured to send the CSG ID and the cell accessmode to the core network node via a Radio Access Network ApplicationPart message.
 13. A method, in a home base station operating a closedsubscriber group (CSG), for performing a handover of a mobile terminalfrom a macro wireless network to the home base station, the methodcomprising: determining that a radio network controller in the macrowireless network is requesting a handover of a mobile terminal to thehome base station, for inclusion in the CSG; determining, responsive tosignaling between the home base station and a core network nodeassociated with the macro wireless network, whether the mobile terminalis eligible for inclusion in the CSG; and deciding whether to admit themobile terminal to the CSG or whether to prioritize the mobile terminal,based on whether the mobile terminal is eligible for inclusion in theCSG.